Distillation of glycerin



June 427, 1939.

#A www ai Ariled Dec. 23, 1935 ML H. ITTNER DISTILLATION oF Gmrcmuu.v

6 Sheets-Sheet l,

ATTORNEYS June 27, 19,39.

DISTILLATON OF GLYCERIN Filed Dec. 23, 1955 M. H. ITTNER 2,164,274

6 Sheets-Sheet V2 'S Pnssuns STER m SUPERHEHTED TERM E /L/ /2 /Z ATTORNEYS June 27, 1939.

M. H. ITTNER DIs'rILLATIoN oF GLYCERIN Filed Dec. 23, 1955 6 Sheets-Sheet 5l INVENTOR M/Mwu/f ATTORNEYS June 27, 1939. M. H. ITTNER 2,164,274

DISTILLATIONOF nwcmuu Filed Dec. 2:5, 1935 A 6 sheets-sheet 4 TEHM VAPoRS DENER WHTER l VnPoRs Cou ENTRHTD INVENTOR ATTO RNEYS June 27, 1939.

`M. H. ITTNER DISTILUA'rLoN 0F GLYCERIN s Sheets-sheet 6 Filed Dec. 25, 1935 INVENTOR HMM# VM-11 M v Maude ATTORNEYS Patented June 27, 1939 j UNITED STATES, PATENT or-i-lcr-LV v nls'rnLA'noN 0F GLYCERIN Martin Hill Ittner. Jersey City, N. J., assigner to Colgate-Palmolive-Peet Company. Jersey City. y N. J., a corporation of Delaware Application December 23, 1935, Serial No. 55,783 A 1o calms. (ci. 2oz-39) This invention relates to improvements in the various steps, certain of which. and certain com- -distillation of glycerin. binations of which, are new and useful. and

The improved methods of the present invenwhich are advantageously combined in the comtion make it possible to' distill glycerin with plete process. The invention comprises or ingreater economy of steam consumption than has cludes the following process steps and combinaheretofore been realizable, while at the same time tions:-The rapid and ellective distillation of A giving a distillate of improved quality without the glycerin with the heating of the glycerin in the need of redistillation, and with substantially comstill by a plurality of closed steam-heating coils. plete recovery of the glycerin as concentrated and with rapid and effective circulation of the l refined glycerin, and with recovery of the greater glycerin over said heating coilslby the injection w part of the glycerin directly as the highest grade of a plurality of Jetsof superheatedsteam therein. of C. P. glycerin. while maintaining a suitable vacuum, the distribu- An apparatus adapted to carry out the process tion of theindirect steam-heating coils. and the of the invention includes a still provided with a introduction of the steam jets, being such as to l5 plurality of closed steam-heating coils located in insure a rapid and thorough and uniform heatl5 the lower outer part of the still for heating the ing of the body of glycerin in the still to maincontents of the still with high pressure steam; tain a substantially uniform temperature: the steam operated ejector jets for mixing the convaporization of distilled water and the passing of tents of the still with steam, the jets being so the resulting steam through a superheating coil located as to discharge a mixture of said still located within the still where the steam is pre- 20 contents with steam into said heating coils to heated to a temperature approximating that of i bring about uniform and effective heating and the glycerin in the still, andthesuperheated steam the production of glycerin vapors; a superheating then discharged through such jets into the glyccoil located within the still for superheating the erin to eifect agitation and aid in the distillation 1; steam before it is discharged into the still conof the glycerin; the condensation of water from g5 tents through said jets; vapor pipes for conductthe high pressure steam used for heating. the ing the vapors from said still through an entrainwithdrawal of said water, the reduction of presment separator to a primary condenser for the sure thereon, and the subsequent vaporizatlon of glycerin; a primary condenser in the form of a said water, or part thereof. to supply pure steam combined boiler, condenser and heat interchanger to be superheated within the still and discharged 30 for the simultaneous condensation of the glycerin through the steam jets into the contents of the and the generation of steam in the boiler by the still; the utilization of heat recovered from the boiling ofdistilled water; means for collecting condensation of glycerin in evaporating pure the condensed water from the closed'steam-heatwater to furnish the open jet steam utilized in ,i ing coils and ofutilizing the same and for supplydistilling the glycerin. this steam being free from y ing the same or a portion thereof tothe combined contamination by volatile impurities derived from boiler and condenser to be there converted into impure glycerin; the utilization of the condensed steam; means for supplying steam from said water, condensed from the high pressure steam boiler-condenser to the superheater coil located used for indirect heating of the glycerin. as the 40 in the still and thence to the jets; means for colwater to be distilled by indirect contact with the 4o lecting the glycerin condensed in said boiler-conhot glycerin Vvapors to be cooled and condensed. denser.; a condenser-concentrator for condensing` and the supplying ot the resulting steam. free the balance of the glycerin from' the vapors of said from contamination with volatile impurities destill as glycerins and aqueous glycerin solutions rived from impure glycerin, to thesuperheating 1.3 of various concentrations, with means for concencoil and steam jets in the still. to aid in the dis- 45 -trating the more dilute giycerins and aqueous tillation; the preheating of the glycerin supplied glycerin solutions condensed within said conlto the still by circulating into indirect contact vdenser-concentrator to produce concentrated therewith the condensed water separated from glycerin with means for drawing of! and collectthe high pressure heating coils.'or vapors pro- .tn ing said vconcentrated glycerin; and means for duced from said water afterv it has been with- 5o conveying excess water vapors from said condrawn and after reduction in pressure to a `lower 1 denser-concentrator to a suitable vacuum appapressure than that oi' the high pressure, heating ratus so as to maintain a suitable partial vacuum coils; the regulation of the condensation of thev within the still and condenser; glycerin vapors by passing them into indirect con- 5 `The improved process of the invention includes` tact with water to be evaporated so that prac- 5g tically pure lglycerin is recovered; the further condensation of glycerin and water, and the concentration of the aqueous glycerin, by a combined condensing and concentrating operation whereby practically all the remainder of the glycerin can be recovered as refined concentrated glycerin, without redistillation; Aan improved method of effecting thecondensation of glycerin in said combined condensing and concentrating operation in which the hot glycerin vapors mixed with steam pass upwardly over a large number of condensing pipes or surfaces in indirect contact with water flowing in a generally descending manner,

and with supplemental heating of the condensed glycerin to increase the concentration of ther glycerin thus directly recovered. The invention includes other specific features of the process, and

4 various combinations thereof, as well as various steps and lsub-combinations of steps of the DIOCQSS.

I have made a 'study of the concentrations of mixtures of pure "glycerin and water that will exist in the presence of an excess of water vapor Uunder various conditions of heat and pressure unfavorable to the liqueication of pure water vapor, and the concentrations of glycerin and glycerin solutions that will condense from a mixture of glycerin and water vapors under such conditions, and have found that in each case the concentration of the liquid glycerin or aqueous glycerin solution that will exist in a state of equilibrium in the presence ofv excess water vapor is very definite and is dependent solely on ,the pressure vapor. that may be present.

structed still the mixture of glycerin and water vapors leaves the still in a condition of delicate equilibrium with respect to temperature and pressure, which equilibrium will be maintained .without sensible precipitation of glycerin through the gooseneck of the still and an entrainment separator when these are properly covered with good heat insulating materiahand that thereafter any drop in the temperature of the mixed vapors will cause a precipitation of glycerin, the concentration of which will depend on the pressure of the surrounding vapors and the temperthe amount of water vapor present.

I have thus 'found it practicable to condense most of the glycerin passing from my still at a carefully controlled comparatively high tempertion to give pure glycerin direct of high concentration, 99% to over 99.5%, and under conditions so that substantially all `of the volatile imfpurities present in the vapors remain in a volatile condition and pass of! with the water vapor without contaminating the glycerin thus condensed. I have also devised a simple means for condensing the' glycerin distillate so that the heat of substantially eighty percent,'or more, of the live steam furnished to run the still, exclusive of that required to overcome heat lost by radiation, maybe recovered and utilised in the process.

I have also devised a system of natural thermal circulation of the still contents for intimately mixing the open jet steam used, in an extremely iinestat'e of division, with the still contents in l "the, zone of maximum heat supply, vso that a balanced condition yof stillcontents, glycerin vapor andwater vapor is easily maintained within the 'still with a lowf'p'roportionof water vapor. 8o

vintimate is th'e of the still contents and and temperature regardless of the excess of water I have also found that in a properly conature of the precipitated glycerin regardless of ature which is sufllcient at the pressure of operanection with the accompanying drawings, which shown, in a somewhat conventional and diagram- `matic manner, apparatus adapted for the practice of the .process of the invention, but it will be understood that the invention is not limited thereto.

In the accompanying drawings:

`Fig. 1 is an elevation, showing one arrangement of the various parts of the apparatus;

Fig. 2 is a vertical section, with parts in elevation, of the still proper;

Fig. 3 is a horizontal section taken on the line 3 3 of Fig. 2, and with certain parts omitted for simplicity of illustration;

Fig. 4 is an enlarged section of one form of steam jet;

Fig. 5 is a vertical section with parts in elevation of the primary condenser or combined boiler-like condenser;

Fig. 6 is a vertical section of the condenserconcentrator, with parts in elevation; and

Fig. 7 is an elevation of. the condenser-concentrator, taken at right angles to that of Fig. 6.

In Fig. l, the still I, in which the glycerin is distilled, lis shown as provided with a goose-neck 2 for the transfer of mixed glycerin and water :A

vapors to the separator 3 to remove entrainment. Leading from the separator is another vapor pipe 4 leading to the primary condenser or boiler-condenser B which serves the dual purpose of condensing the greater part of the glycerin and of recovering the heat therefrom for generating steam by the evaporation of distilled water, which steam is utilized directly in the still to supply pure open jet steam, and the balance of which'is utilized elsewhere in the system as will be subsequently explained.' Connected with the lower part of the boiler-condenser 5 is a vapor pipe 6 for conveying water vapors mixed with glycerin vapors not condensed in the boiler-condenser 5, together with substantially all the volatile impurities from the still, to the combined condenser-concentrator 8. Located below the boilercondenser 5 is a tank 1 for the reception of the pure glycerin condensed in this condenser; while a tank 9 is likewise arranged below the condenser-concentrator 8 to receive the glycerin concentrated from the condensates produced in the combined condenser and concentrator. The

. outlet pipe III is provided for conveying the water vapors and substantially all of the volatile impurities to the vacuum equipment (not shown) for removing the water and impurities and for maintaining the necessary vacuum. The outlet pipe Il is shown as having an upward inclination of about 10 from th'e horizontal, so that any condensate condensed therein will bereturned to the condenser-concentrator. The entrainment separator 3 may be of any suitable construction, for example, such as the Webre separator, but it should not offer any obstruction-to the free ilow of vapors therethrough.

As illustrated in Fig. 2, the still l is heated by closed steam heating cous ||,|z, n, u and is,

controlled by inlet valves A,B, C, D and E'and outlet valves a, b, c, d and e. The inlets to these Til closed coils are connected to the pipe S through which steam is 'supplied at a suitable pressure, e. g., of varound 150 gauge pressure from 'a source of high pressure steam (not shown). Saturated steam, supplied under pressure, serves to heat the contents of the still. The water condensed from the` steam under pressure is withdrawn through the outlet valves a, b, c, d and e to the header I8 and thence through a trap I9 which permits only water, and no steam, to pass therethrough, so that escape of high pressure Vsteam from the heating coils is prevented. The outlet of the trap I9 is connected by pipe 20 to the receiver I1, which has a suitable pressure relief valve 25 therein which determines the pressure maintained in the receiver, e. g., a pressure oi about 25 pounds. `The hot water entering the trap under the high pressure, e. g., of around 1,50 pounds, is discharged from the trap to a zone of lower pressure, i. e. that in the receiver I1.

The condensed steam is still at a high temperature when the pressure is released upon it at the trap i9 to the lower pressure controlled by the valve 25, and the reduction in pressure causes vaporization of a part of the hot water at the lower pressure prevailing in the receiver I1, part of the heat of the hot water being utilized to vaporize a portion oi?l the water and generate steam therefrom at a lower pressure, the remainder of the water being still hot and at a temperature corresponding to the temperature'of saturated steam at the lower pressure maintained in the receiver I1. For example, if the high prssure steam used in the heating coils is supplied at a pressure of around 150pounds gauge and at a temperature around 366 F. or 185.5 C. the condensed water leaving the coils and passing to the receiver I1 will be at a temperature not greatly below that mentioned at the time the pressure is released. The temperature of saturated steam at a pressure of e. g., l25 pounds gauge maintained in the receiver I1 is around 267 F. or 130.5 C. The heat contained in the hot water at the higher temperature and pressure is utilized in distilling part of the water and generating steam therefrom on reduction of pressure; and both theresulting steam and the remaining unvaporized hot water,A at the somewhat lower temperature and pressure, are advantageously utilized in the process.

Leading from the top of the receiver I1 is a steam pipe 2| which conveys the steam to a crude glycerin heater 22 for preheating the crude glycerin before` entering the still'. The outlet from this heating chamber 22 has a trapv 23 therein to permit the removal of condensed water but nosteam and a relief valve 24 to blow oil' at some desired pressure as for instance about 25 pounds gauge pressure, and preferably at a slightly higher pressure than relief valve 25 on receiver I1. The outlet line 21 from the bottom oi the receiver I1 has a trap 26 therein to prevent passage of steam while permitting passage of water and this outlet pipe 21 leads to the Water cooler 2B for cooling the distilled water from the receiver I1 toa lower temperature, when desired,

`for example, to around 190 F. before it is supplied through the pipe 29 to the boiler 5.

The boiler 5 is provided with a relief valve 30 through which `excess steam may be discharged automatically to prevent accumulation of excesxv 32. and valve 33 therein. The top of the superpressure steam line S through the orifice 34 and valve F so that the high pressure steam can be used, with suitable reduction in pressure, in the' superheater coil at such times assteam from theV boiler 5 is not available or as a separate and independent source bf steam to the superheater coil.

ll'he superheater coil I6 as shown in Fig.- 2 is i arranged inside the closed heating coils II to I5 swirl and stirring action to the contents of the still, thereby effecting continuous and rapid circulation of the contents of the still over the heating coils. The arrangement is such that the steam discharged through these jets, and the lntimat'ely admixed liquid, will rise through the coils I j, I2, i3, I4 and I5 and will carry the still contents upwardly over and among these heating coils, causingeffective agitation and circulation of the contents of the still upwardly through and around these heating coils and downwardly through the central portion of the still inside the superheater coil I6. i,

As shown in Figs. 2 and-3, perforated steam rings 4I, 42 and 43 are located near the bottom of the stilland are connected with the high presi' sure steam line S through separate connecting pipes having valves G, H and I and oriilces 38, 39

andd. Rings 4I and Hare shown so placed and with the orifices so arranged that the steam will be discharged therefrom upwardly through the heating coils II to I5 which the ring 43 is shown placed near the center and bottom of the still for use in washing out the still foots or residue after distillation. l

The still is also shown as provided with peep glasses 66 on the cover of the still, with gauge glass 10 on the side of the still to indicate the level of the contents and a run-off outlet with valve 1I therein for emptying the still.

The boiler-condenser 5 oi' Fig. 1 is illustrated in greater detail in Fig. 5. This boiler-condenser is constructed as an indirect heat interchanger since it is essential that the cooling water and the vapors cooled shall be kept separate from each other. lThis boiler-condenser serves as a condenser for glycerin vapors and as a boiler for the generation of steam, the water in the boiler serving as cooling water for cooling and condensing the glycerin vapors, and the heat of the glycerin vapors serving for the evaporation of the distilled water in the boiler under a suitable pressure, preferably superatmospheric pressure.

The boiler is supplied with distilled water from' the receiver I1, at a regulated temperature,

' through the inlet pipe 29,' and the boiler has a relief valve 30 and steam pipe 3| leading to the superheater coil I6, as already described. The

'inlet for the glycerin vapors entering through the pipe 4 is shown as connected to the topv of the boiler-condenser and a plurality of tubes 56 are provided. through which the glycerin and water vapors from the s till pass downwardly, these tubes being surrounded and cooled by the distilled water in the boiler which is converted into steam by the heat absorbed from the glycerinheater coil I5 is also connected with the high' and water vapors in condensing the glycerin therefrom. The tubes 56 are shown as provided with spiral or helical inserts 51. These spirals may be made from thin metal twisted slightly so as to assume a helical or screw shape and it is desirable that these spirals shall have one or more turns during their length so that the vapors cannot pass through the tubes without being deflected continually toward the sides of the tubes. While the boiler may be constructed so that the vapors of glycerin and water vapor pass upwardly through the tubes 56, there are distinct advantages in passing them downwardly through these tubes. With the helical insert shown, the line of greatest slope from any part of the tube in contact with the edge of the spiral is rapidly toward the center of the spiral and down the center of the spiral so that the condensed glycerin is kept near the center of the spiral and away from the tubes, rendering the tube condensing surfaces more effective, while the helical shape of the spiral causes the downwardly directed vapors to be continuously deflected toward the sides of the tubes. The arrangement is thus such as promotes effective heat transfer to the surrounding water from the vapors passing over the interior surfaces of the tubes. The spiral inserts are shown as having their lower portions straight at their lower ends for a few inches so thatI the downwardly flowing vapors will leave the tubes in a straight direction rather than with a strong swirl that would tend to break up the glycerin streams into tiny droplets and thus increase entrainment. These spiral inserts are also shown as stopping a short distance above the lower ends of the tubes.

Arranged below the tubes 56 is a pan 58 for catching and collecting the condensed glycerin. This condensed glycerin is in the form of a multitude of streams flowing from the lower ends of the tubes and is thus collected and separated from the onrushing mixed glycerin and water vapors which pass laterally and around the pan 58. -The condensed glycerin that falls' into the pan 58 is conveyed down the pipe 59 and is delivered on to the top of the end of the cross pipe 5 around which it flows and then passes downwardly into receiving tank 1 for removal in the boiler. Il.

and use, the connecting pipe having a valve 12 therein. The balance of the glycerin which is condensed in the boiler-condenser 5 and does not vfall into'the pan 5B is conducted downwardly through the opening 59a so that it also flows over .thepipe 6 along with that flowing down through the pipe 59. .Y

The mixed glycerin and water vapors leaving the boiler-condenserA 5 pass downwardly to the space 60, surrounding the end of the pipe 6,

and then through the cross pipe 5 and the space' BI surrounding the other end of this pipe and thence upwardly into the condenser-concentrator I. y A

The boiler-condenser is shown as provided with la gauge glass 52 and an overflow trap 63 to maintain the level of the distilled water in the boiler sothat it willalways'cover the inner dome 64. The trap 63 as shown is arranged to remove boil- `ing'water at the water-steam level; or it may be .located at the desired water level on a pipe ,I (not shown) leading from the -hot water pipe Il at the bottom of the boiler to thetop of the boiler, in which case it will prevent water from entering the boiler in excess of that required I also find it advantageous to provide an expansion joint 65 between the upper portion of the inner condensing section of the boiler' and the outer shell of the boiler to prevent the formation of undue strains in the tubes 56 or ground sheets due to uneven expansion between the boiler shell and the condensing parts. The boiler 5 is shown as having a steam outlet pipe 52 leading to the bottom rows of tubes in the condenser-concentrator l for heating the same, as hereafter described,' and the outlet 53 from these tubes has a pressure relief valve 54 and a trap 55, as shown in Fig. 1, the pressure relief valve 54 controlling the pressure .in the boiler 5 and being set at the desired pressure, e. g., 20 pounds absolute, while the trap 55 permits water condensed from the steam to escape without permitting escape of steam.

The boiler-condenser 5 may be so designed thatl the condensing surface will be suilicient to condense substantially all of the glycerin; but if this is done the glycerin thus obtained will contain an appreciably higher percentage of the objectionable volatile impurities, and, in order to make the condensation substantially complete, it would be desirable if not necessary to reduce the temperature of the Water in the boiler either by operating at a reduced pressure or by constructing the boiler so that it would have a lower cool'er section. In either event the concentration of the glycerin that would be condensed would be appreciably lower and less desirable than the concentrations which I have obtained, and the quality of the glycerin would be lower owing to a greater absorption of objectionable volatile impurities at the lower temperature and lower concentratlons.

In order to obtain glycerin of high plnity and suiiiciently free from objectionable volatile-impurities I find it advantageous to design the boilercondenser 5 so that the condensing surface will not be suicient to condense all the glycerin, but

so that a large part of the glycerin will nevertheprimary condenser 5 in amounts ranging from d less than 75% to more than 90% of the distillate; butI have found it advantageous, all things considered, yto operate so that about 80% of the glycerin is condensed in the primary condenser 5 at about 99 to 99.5% concentration.

The combined condenser and concentrator 8,l

shown in Fig. 1 and illustrated in more detail in Figs. 6 and 7, is provided with a plurality of banks of condensing and concentratingpipes M. These are cooled near the top of the condenser with cold water entering at 45. The condenser-con- .centrator 8 is so designed that the cold water entering at the top will flow gradually downward, instead of upward as is customary .in 'surface condensers. In order that the condensing and concentrating pipes may at all vtignes be filled with water in that portion of --the` apparatus through which condensing water is:l allowed to flow, and not accumulate air or steam in pockets, I have devised an arrangement of the pipes so that the ow of water will be locally 4upward through the tubes 44, though generally downward. This` is accomplished by permitting the cold condensing water toenter at the inlet 45 which is at the second bank of tubes from the lli) top, and causing the 'water to ow rst through the tubes of this bank and then through the tubes of the top row and out at the outlet 50 from the top row to an outlet which connects with an inlet 5I to the fourth row from the top, so that the water iiows through the fourth row and then through the third row from the top, then downwardly to the sixth bank or rows of tubes and upward to the iifth bank of tubes, andso on.

By reference to Figs..6 and 7, it will be seen that there are smaller tubes 41 located within the larger tubes 44, and that the small inner tubes 41 connect with slotted spaces 46 at their ends, while the outer larger tubes 44 hav'e slotted spaces 49 at one end connecting the ends of two adjacent rows o'i tubes. The smaller tubes, at their inner ends have a small spur 41a on their under side for support and open into the larger tubes, as shown. The arrangement is such that the water which enters the second slotted space 46 leading to the inner portions of the inner tubes 41 of the second bank of tubes, passes through these tubes and into the space 48 between the smaller tubesA 41 and the larger tubes 44 of the second row of tubes, then out of the ends of the larger tubes into the space 49 and then to the ends of the larger tubes of the top row, then through these large tubes and back through the smaller tubes to the slotted space 48 of the top row of tubes and then out at 5U. Since the outlet is from the upper row of tubes, any air or vapors are forced outwardly with the water and down into the inlet oi.' the fourth `row of tubes. The arrangement is such that the water from 4the upper row of tubes passes down into the slotted space at the ends of the small tubes of the fourth row of tubes, then through the tubes ofv this fourth row, in the manner described, and then upwardly to the third row and through the third row of tubes, and then outwardly and down to the inlet of the sixth row of tubes, and then through the sixth row and the fifth row, and so on. `In the alternate rows of tubes, e. g., the second, fourth and sixth rows, etc., the flow is inwardly from the slotted spaces 4S to the inner small tubes 41, then back through the space 48 between the inner tubes and the outer tubes, .then upwardly through the slotted space 49 to the inlet of the larger tubes of the next row, then through the space between the larger tubes and the inner tubes, and back through the smaller tubes to the slotted space 46 of this next higher row, e. g. the first, third, and

iifth rows, etc.

The water may thus be led through all oi' the banks of tubes and be withdrawn from the outlet at the next tothe bottom row of tubes; or the condensing water can be withdrawn before permitting it to traverse all of the banks of tubes. This latter arrangement is an advantageous one since the lower rows of tubes can then be utilized for heating the. lower part ofthe condenserconcentrator. In the apparatus illustrated in Figs. l, 6 and '1, thewater outlet is from the fourth row of tubes from the bottom, through the outlet pipe l15.

The lower two rows of tubes in the condenserconcentrator 8 are shown as connected with a steam supplyior heating these tubes. The steam line 52 from the boiler 5 enters the Vnext to the bottom row of tubes so that the steam can pass through this row of tubes and then through the lower row of tubes and then to the outlet 53. above referred to.` Such an arrangement provides for heating one or more pairs of rows of tubes at the bottom oi' the condenser-concentrator with steam to increase the concentrating e'ect instead of depending on hot4 water gradually heated by theheat absorbed in its down- 'ward iiow through the tubes of this apparatus. In the arrangement illustrated in Fig. l, steam is supplied to the two bottom rows of tubes by utilizing part oi.' the excess steam generatedin the boiler 5, in excess of that required for supplying the open jet steam required in the still l for distilling glycerin.

By reference to Fig. it will be seen that the tubes of the different rows or banks in the condenser-concentrator 8 are not placed directly under the tubes ci the next higher row or bank, nor are they placed directly under the spaces between the tubes of the next higher row or bank. Instead, the tubes of each bank are shifted slightly side-wise from the tubes of the bank immediately above and below, with the result that vapors may not travel directly through the banks of tubes without being diverted in their course, and with the further result that water and dilute glycerin solutions condensing on the upper colder tubes may not drip olf through the open spaces of the tubes beneath but will fall so as to strike the tubes of the next lower bank. 'I'his arrange-` ment is an advantageous one, since, in this way, the more dilute glycerin solutions condensing on the upper, colder tubes fall in their downward course to successively hotter and hotter tubes, and there lose a portion of their water and become progressively more and more concentrated until they reach the bottom tubes which are at the highest temperature, and where it is desirable to heat the tubes with steam from an outside source or hot water that may be permitted to reach the boiling point through heat accumulated by the condensation of aqueous glycerin solutions in this part of the apparatus and by absorbing heat in cooling the hot vapors entering at the bottom of the condenser-concentrator B.

The tube surface maintained in the condenser? concentrator 8 is suicient to condense all of the glycerin asaqueous glycerin solutions of various concentrations, depending on the temperatures of the water in the various banks of tubes; but the total tube surface is preferably not suiiicient to condense more water as water or dilute glycerin thancan be re-evaporated by the excess heat of the vapors entering at the bottom and absorbed by the tubes and accumulated in the lower banks of tubes, or by excess heat in the form of steam suppliedto the lower banks of tubes. 'I'he arrangement is advantageously such that the glycerin is condensed with substantial completeness before the cooledV vapors leave the upper rows of tubes, so that practically glycerin-free water vapor, etc., leaves the top of the apparatus; while the heat interchange and heating of the condensed glycerin is advantageously such that the glycerin which nally flows from the bottom rows of tubes, after concentration thereon, is concentrated glycerin.

In the drawings, no heat insulation is` shown on the apparatus, but it will be understood that, in actual construction and operation, goed heat insulated covering will be provided on the still- I, the goose-neck 2, separator 3, vapor pipes 4 and 6, boiler 5 and tanksv 1 and ,as well .as on all outside steam pipes and the receiver I1A and the connecting pipes between the boiler l and receiving tank 1 and also the connections be- .tween the condenser-concentrator 0 and the I., It is also desirable to coverthe crude glycerin heater and the pipe 68 for conveying preheated glycerin to the still, with heat insulation. -This supply of preheated crude glycerin is regulated in flow by the valve 69.

'A valve 12 is provided in the pipe that conducts glycerin from .the condenser-boiler 5 to the tank 1 and a valve 13 is provided in the pipe that conducts glycerin'V from the condenser-concentrator 3 to the tank 3. Tanks 1 and-9 are also provided with gauge glasses for indicating the height-of glycerin therein, and also suitable run-of! pipes and valves and vacuum breaks, and connections to auxiliary vacuum apparatus (not shown), which may be employed in emptying the tanks 1 and l without interrupting the progress of the distillation.

It will be understood that the vacuum gauges and pressure gauges will be supplied where necessary on the apparatus. Thus the goose-neck 2 may be provided with a suitable vacuum gauge, conventionally shown, and the boiler 5 with a pressure gauge, similarly shown. 'It will also be understood that thermometers will be provided, where necessary, to show the temperature of the liquid or vapors in different parts of the apparatus, for example, the temperature of the hot distilled water entering the boiler 5, the temperature of the hot water flowing from the lower part of the condenser-concentrator 8, etc.

The entrainment separator 3, which may, for example, be a Webre separator, is shown as provided with a drain line 14 leading back to the still I. This line should also be carefully covered with insulating material.

Suitable peep glasses may be provided on different parts of the apparatus to permit observation of the progress of the distillation and condensation such as the peep glass 66 on the still cover and the peep glass 61 on the dome of the condenser-concentrator.

When the apparatus is in operation, and distillation is progressing, the water in the boiler l is kept boiling, and it will remain hot during short shutdowns. In starting distillation, after a long shut-down, as for instance over the week end, the water in the boiler 5 may be brought quickly to the boiling point by running in live steam directly into the boiler from a pipe and valve (not shown).

The combined area of the high pressure heating coils II to Il in the still I is purposely greatly in excess of what is needed for continuous distillation, in order that the still contents may be brought rapidly to the boiling point at the start of the distillation and thus minimize the time of shut-downs.

In the distillation of glycerin in the apparatus and in accordance with the process of the present invention, I maintain a suitable vacuum in the apparatus which may be, for example, at an absolute pressure of 15 millimeters of mercury. It is not necessary to maintain this particular vacuum, as the process can be operated satisfactorily with either a better or poorer vacuum and over a fairly wide variation of absolute pressure.

- In starting the operation of the apparatus, all

l outside valves are rst shut anda partial vacuum bottom of the side of the still with its lower end slightly above the center of the ejector jets 31 -within the still, I open at once valves A, B, C', D and E. and valves a, b, c, d and e, and also valve F leading from the high pressure steam line through a suitable orice 34 to superheater coil II, ring manifold 35, pipes 36, and ejector jets31. During thisltime valve 33 is closed. In this way the high pressure steam is utilized in the closed heating coils for rapidly heating the apparatus, and the same source of steam is also utilized, with suitable reduction in pressure, in the ejector jets 31 for bringing about thorough and effective circulation and agitation of the liquid contents of the still. v

Coincident with the starting of the vacuum, when the water in the boiler 5 is cold, I open a live steam line (not shown) and admit live steam into the distilled water in this boiler to bring this water to the boiling point, after which the live steam is shut off and no longer needed.

With the large excess of heating surface in the coils I I to I5, the contents of the still are brought to a boil in a few minutes at the partial vacuum then maintaining within the still and even before the nal vacuum is built up. The agitation of the contents of the still by the steam entering through jets 31, and the expansion of the finely divided steam particles released through the jets 31 cause the still contents to rise and cover all of the closed steam coils and to ilow rapidly upwards through these coils, with an inward side-wise motion such that the flow is through the superheater coil I6 and downwardly within the space inside this coil I6 to the bottom of the still, rapid circulation of the contents of the still being thus accomplished.

The level of the still contents within -the inner bounds of the superheater coil IB is normally a foot or more below the level of the still contents rising through and over the coils II to I5 and pouring side-wise through and downwardly over the inner portion of the superheater coil I6. The circulation of the contents is so rapid, and the space between the turns of the superheater coil is so restricted that the general circulation is upwardly through the heating coils on the exterior of the superheater coil, and largely downward inside the superheater coil, with some flowing sidewise between the turns of this coil. So perfect and uniform is the mixing of -the steam and the still contents, brought about by the ejector jets 31, that the contents of the still do not bump or surge or swell higher than about the top of the superheater coil I6, and there is no danger of any of the contents swelling over or spitting or bumping over, as the contents of the still at no time become locally superheated.

As a result of this rapid and uniform and effective circulation of the entire still contents, and the intimate contact of the jet-steam with the liquid. and the rapid flow of the contents over the superheater coil, there is only a small difference at most between the temperature of the liquid contents of the still, the temperature of the vapors leaving the still, and the temperature to which the steam is superheated in the superheater coil before it is discharged into the liquid contents of the still. The superheating of the steam, in the superheater coil I3, is thus accomplished by the liquid contents of the still, at a higher temperature than that at which the saturated steam is supplied to the coil, so that this steam is superheated to practically the temperature of the liquid contents of the still before it is introduced through the ejector jets into such contents.

By starting a still in the manner described I have been able to start a still that had been emptied and opened to the air so that it was distilllng glycerin at a. rapid rate within lteen minutes after starting the vacuum apparatus. The glycerin vapor thus formed and passing through the gooseneck 2, separater 3 and pipe 4, enters boiler and begins to make steam therein, due to the latent heat given up by the glycerin vapor in condensing to a liquid. The steam thus formed' begins to build upa pressure in the boiler 5, and

as soon as this pressure reaches about 4 pounds per square inch gauge pressure, the valve F from the high pressure steam supply line is closed andI the valve 33 is opened to permit the steam generated in the boiler to enter the superheater coil I6 through oriiice 32. The orice 32 issomewhat larger than oriiice 34, as it is suppiied with steam at a lower pressure than that which passes through the orifice 34. I'he sizes of .both of these orinces are so calculated as to take these different steam pressures into account and to deliver the desired amount of open jet steam.

means of the release valve 54 at about 5 pounds gauge pressure, or about 20 pounds absolute, there will be about 18 pounds differential pressure between the steam entering the orice 32 and the still contents, causing a rapid blast of steam to pass through the ejector jets 31.

The jet steam, at the moment of entering the still contents. expands fully ten-fold, due to the sudden decrease in pressure, and causes an enormous amount of the liquid still contents to pass through the ejector jet 31, due to the ejector action. This liquid becomes most intimately mixed with this expanding steam at the instant that the mixture is being discharged upwardly through the heating coils II to I5.

Operating in the manner described, I have found it possible to condense 80% or more of the glycerin distilled in the boiler 5 and collect this glycerin in the tank 'I in a high degree of purity. The rapidity oi distillation may be observed by watching the change in height of glycerin in the gauge glasses located in the sides of the tanks 'I and 9, thus indicating ythe levels of distilled glycerin within these tanks.

The present process can be operated with varying amounts of open jet steam. I I have operated, for example, with the use of 400 pounds of open jet steam per hour in the still while producing about 1000 pounds of glycerin distillate per hour. This amount of open jet steam is considerably less than has been customarily used heretofore. I have found that 4a somewhat smaller or larger amount oi open jet steam can also be used with good results. The orifice 34, or the orice 32, through which the steam is supplied to the superheater coil and to the ejector jet. are of such a size that they will deliver a. proper amount of steam, e. g., 400 pounds per hour. and the amount of open let steam thussupplied can thus be regulated and controlled.

In the operation oi the apparatus, after the still has begun to operate in the manner previously described, it is generally ldesirable to shut ofc' part oi the steam entering through the coils Il to I5.. This can be done by closing one ormore o! the valves A, B, C, D and E and the corresponding valves a, b, c, d, and e.` I have found that the heat supplied by asingle coil would usually be suicient to maintain a. fair rate of distillation, but that it is preferable tol use two or three coils, and, toward the end of the dis- If -the .steam generated in the boiler 5 is maintained by tillation, to turn on additional coils in order to maintain a high rate of distillation at all times.

The heat for the distillation is supplied mainly by the closed heating coils, and at the high temperature obtainable with high pressure steam, but local overheating of the still contents is avoided by the uniform and thorough circulation and agitation of the still contents by the use of the ejector jets for the direct jet steam.

I have found that a separate outside super# heater for superheating the open jet steam is not necessary. The heat necessary for superheating the steam is relatively small, requiring only about two or three percent of the heat furnished to the `still by the heating coils Il toY I5. By arranging the superheater coil in the still where it does not absorb heat from the still contents in the zone where heat supply is most needed, or lessen the capacity of the still, this superheater coil will readily absorb sufficient. heat from the still contents to give the desired superheat, and to bring the steam to practically the temperature of the still contents, without the need of an outside superheater. The general circulation within the still, previously described, is such that vaporization takes place largely from that portion of the still outside the superheater coil, and around and v above the heating coils I I to I5, and the circula- 'tion of the liquid, from which the vapors 'are largely removed, inwardly and downwardly over and through the superheater coil, results in eiective heating of this coil by the still contents, without objectionable cooling of the still contents or interference with effective distillation thereof. Heat losses through the use of an outside superheater are thus avoided.

In distilling soap lye crude glycerin which' contains an appreciable percentage of salt it becomes due. To accomplish this, when the feed of crude glycerin to the still is discontinued, the distillation is allowed to proceed until the level of the still contents drops to the bottom of the gauge glass. All valves A, B, C, D, E and a, b, c, d, e may then be opened wide and valve 33 closed. .At the same time valves G and H are opened wide permitting open jet steam from the 4high pressure main S to enter through oriiices 38 and 39 to ring jets 4I and t2. Oriflces 38 and 39 are of-such a size that together they will permit a properly controlled amount of steam to pass, say about 400 pounds per hour.

In this way the greater part of theglycerin may be rapidly distilled from the still residue. The distillation may then be stopped and the vacuum may be broken and the still foots may be washed out' with hot water in a suitable manner. The still can thus be made ready in a short time for further distillation. At the same time it is advantageous to remove the distillate from tanks 1 and 9. In beginning a new distillation closely following another, no auxiliary heating of the distilled water in` boiler 5 is necessary.

Afterv a distillation is started, as described, the distillation is almost automatic and one operator has plenty of time to attend to several stills, the starting times of which may be staggered. During the course of distillation the operator secs that the level of the still contents is maintained substantially constant as indicated by gauge glass fdl 10, by the feed control valve 69 and that the temperature of the hot water entering boiler 5 and the hot water coming from condenser-concentratorare maintained near the desired temperature. He will also observe that a good flow of cold water enters the top banks of tubes of condenser-concentrator 8 and that the vapors passing out of vapor pipe I0 are not permitted to becgme hot enough to carry any glycerin with t em.

Careful tests of the absolute glycerin fed to my still and of the absolute glycerin distilled and accounted for show that there are substantially no unknown losses in the use of my still, such as might be due to decomposition or vapor losses.

used to furnish heat in the still for the volatilizaw 'tion of the glycerin during distillation. This is a particularly advantageous combination and arrangement and sequence of steps and operations. The high pressure steam utilized for furnishing heat in the still is itself condensed, giving pure distilled water which is supplied to the boiler at a temperature approximating its boiling point and there serves to cool and condense the glycerin,

'while it is itself revaporized to give the open jet steam used in the still. The steam serves, finally, for carrying volatile impurities from the glycerin out of the system through vapor pipe I0. The same steam and distilled water thus serve a quadruple function in the process, and with notable economy in steam consumption, as well as a particularly advantageous utilization of the steam and water condensed therefrom.

In certain of its broader aspects, however, and considering the distillation operation in the still proper as an operation separate from the combined distillation and condensation, the distillation can be carried out with steam derived from some other source, such as by reduction in pressure of the high pressure steam supplied through a suitable controlling valve or orifice, such as provided in the valve F and orifice 34. So also, from the standpoint of generation of steam in the boiler 5, the operation is similar if the distlled water is supplied from some other source than the condensed water from the high pressure steam coils. Accordingly, I do not limit myself, in the broader aspects of the invention, to the use of open jet steam derived from the distillation of distilled water in the boiler-condenser; nor do I limit myself to the utilization oi' the condensed water in said boiler, when the open jet steam is to be generated therein. But I nevertheless claim the process specifically when the open jet steam is derived in the boiler 5, and when the distilled water supplied thereto is recovered from the high pressure steam, since there are approximating the boiling point in the boiler,

so that this water requires little or no'heat to raise it to the boiling point; while it is free from objectionable'volatile impurities, and the open jet steam produced therefrom is likewise free from objectionable volatile constituents. Moreover, the Water itself, being pure condensed water, is free from non-volatile matter such as would leave accumulative and objectionable deposits on the heating surfaces of the boiler, and thereby impair its eiliciency,

Another advantageous feature or operation of the invention is the utilization of the ash steam recovered from the condensed water from the heating coils Ii to I5, generated on reduction of pressure on the hot condensate, for preheating the impure glycerin fed to the still I. This flash steam is capable of utilization elsewhere, and the crude glycerin can be otherwise preheated, but the flash steam is nevertheless a convenient and advantageous heating medium for preheating, the glycerin and,'by its use, added heat economy is obtained, and the heat contained in the condensed water from the heating coils is thereby further utilized to advantage in the process.

So also, in the operation of the process, as heretofore described, the steam generated in the boiler-condenser 5, from heat recovered during the condensation of the glycerin, is advantageously used both for open `jet steam in the still and for heating the lower rows of tubes in the condenser-concentrator 8, for concentrating the glycerin condensed therein. In certain of its broader aspects, the invention is not limited to the use of steam so produced; but steam of equal quality derived from other sources could be similarly utilized without departing from the spirit of my invention, in its broader aspects, even though the utilization of steam otherwise derived would not result in the economies and advantages which I obtain by utilizing heat recovered in the process and when different parts and features are con- The method of vapori sideredby themselves. zation of the glycerin has distinct advantages, regardless of the method of condensation employed. Similarly the method of operation of the boiler-condenser has distinct advantages, regardless of the speciilc method of vaporization in the still, or the method of subsequent condensation of uncondensed glycerin. The method of operation of the condenser-concentrator also presents distinct advantages, regardless of the specic method of vaporization in the still, or the specific method of effecting partial condensation of the glycerin.

In the still proper, and in the method of va*- porizing the glycerin therein, the indirect heating of the glycerin by high pressure steam coils suitably arranged near the outer portion of the still, the use of open jet steam introduced through ejector jets so introduced as to create a rapid circulation of thestill contents and to force continuously a considerable 'portion of the still contents, intimately mixed with the nely divided sprayed steam from the jets, directly against and through that portion of the heating surface having the highest temperature, in such a way as to while avoiding completely the superheating of the still contents, and the use of a superheated eilect the maximum volatilization of glycerin particularly valuable method of distilling glycerin.

This method of distillation, while it utilize's high pressure steamat a high temperature, completely avoids superheating of the still contents such as Vis experienced in old type stills where the steam jet is simply permitted to bubble up through the still contents and where effective means are not employed for the thorough continuous andy rapid circulation of the still contents such as is employed in the present Aprocess and apparatus.

The method of operation of the boiler-condenser enables heat to be recovered in an advantageous and effective manner from the glycerin vapors, while condensing these vapors to give a recovery of most of the glycerin in a state of high purity such that further distillation is not required. At the same time the heat thus recovered is utilized to advantage in the distillation of distilled water and the production of steam free from objectionable volatile impurities which is advantageously supplied as the open jet steam in the vaporization of the glycerin; and the co-ndensed water, condensed in the high pressure heating coils, is advantageously utilized, with reduction in pressure and partial self-vaporization. for preheating the crude glycerin supplied to the still and for supplying hot distilled' Water to the boiler-condenser at a high temperature. Part of the steam generated in the boiler is also advantageously employed in the subsequent condenser-concentrator i'or aiding in the concentration of the condensed glycerin therein.

The improved method of operation involving employment of the condenser-concentrator will effectively condense and concentrate all of the glycerin that is passed through the primary condenser (or boiler-condenser). It condenses glycerin of all concentrations at the same time from the most dilute, which may be practically of zero concentration in the upper part of the condenserconcentrator, to glycerin of around 99% concentration or over in the lower heated portion of the concentrator. This condenser-concentrator is so constructed and operated that the more dilute glycerin solutions condensed in itsupper portion, falling downwardly from one bank of pipes to the next hotter bank, become gradually concentrated to 99% or over, so that highly concentrated glycerin is drawn olf from the bottom of the condenser-concentrator at the same time that the upper colder banks of tubes prevent the volatilization and loss of any appreciable amounts of glycerin from the apparatus.

The following example of the practice of the process Iwill illustrate temperatures and other conditions which may obtain in diierent parts of the apparatus during the carrying out 'of the process:

Assuming that high pressure steam is used at about 150 pounds gauge pressure or at a tem-` reduced by partial self-vaporization, on reduction of pressure, for example, to 25 pounds gauge, so that the water in the receiver has a temperature of e. g., around 267 F. and the steam formed has a similar temperature. The steam used to preheat the glycerin preheats it to a temperature approximating that of the steam used, depending on the intimacy and eillciency of heat transfer.-

The boiler-condenser has the boiler portion containing the hot condensed water derived from receiver l1 at a pressure of, e. g., 5 pounds gauge `and with the steam generated at a temperature of about 228 F. This steam is superheated in the superheater coil, before it is dischargedinto the glycerin through the ejector jets, to approximately'the temperature of the glycerin in the still, e. g., about 320 F.

The admixed glycerin and steam vapors, etc.,

enter the top of the boiler-condenser at approxi mately the temperature at which they leave the still, e. g., at about 320 F., and leave the bottom' of this condenser at a lower temperature, e. g., around 257 F. The condensed water from the receiver I1 enters the boiler-condenser at a temperature which may approximate that of the water in vthe receiver I1 or at a lower temperature. If cooled to, e. g., 190 F. before it enters the boiler-condenser and introduced at that temperature it will have a somewhat greater cooling and condensing eiect on the glycerin than it 'would if introduced into the still at a higher temperature, nearer that of the water in the receiver l1.

The temperature of the admixed glycerin and steam vapors, etc. entering the bottom of the condenser-concentrator may be approximately that of the vapors leaving the boiler-condenser, e. g., around 257, more or less. The vapors of Water and impurities leaving the top of the condenser-concentrator will vary somewhat in operation but may be for example around 120 F., more or less. The temperature of the cold water. entering the top of the condenser-concentrator will vary somewhat with climatic and other conditions and may be, e. g., around 60 F. and may be heated in passing downward between the tubes of the condenser-concentrator to approximately the boiling point or somewhat below the boiling point, e. g., around 150 F., depending upon the amount of water supplied and other considerations. Where the lower rows of coils in the condenser-concentrator are heated by steam the steam will enter 228 F., which may be below the-temperature of the entering vapors of glycerin and water and thus serve to condense some additional glycerin but will also assist these vapors in heating the condensed glycerin which drips down from the higher tubes on to these lower steam-heated tubes.

By operation of the process and apparatus as a whole, I have found that it is possible to recover substantially the entire glycerin distillate in a concentration `of I99 to 99.5% glycerin, without appreciable loss of glycerin through volatilization, and of such a high degree of purity as to make unnecessary the use of subsequent redistillation ofthe glycerin in separate distilling operations.

`'While the present process has, been described in connection with the distillation of glycerin, apparatus and operations involving the same principles of construction and operation may be advantageously utilized in the distillation and puriiication of other volatile substances having. a considerably higher boiling point than at a temperature, e. g., around water and which are miscible with water in their higher and lower concentrations.

In this application I claim the improved process of distilling glycerin heretofore described. but I do not claim the improved apparatus adapted for use therewith, as this is described and claimed in my divisional application Serial No. 84,740, tiled June 1l, 1936.

I claim:

1. The method of distilling glycerin which comprises heating the glycerin under pressure below atmospheric by indirect contact with saturated steam under pressure while injecting steam at lower pressure directly intothe body of glycerin undergoing distillation, with resulting condensation of water from the saturated steam and with vaporization of glycerin, reducing the pressure on the condensed water and bringing it into indirect contact with the hot vapors from the body of glycerin undergoing distillation to effect condensation of glycerin and generation of steam from the water at 4a reduced pressure, separately collecting the glycerin so condensed, and using steam so generated, free from objectionable volatile impurities, as the lower pressure steam injected into said glycerin.

2. 'I'he method of promoting the distillation of glycerin with the aid of open jet steam discharged into the body of glycerin undergoing distillation which comprises bringing the hot glycerin vapors from such distillation into indirect contact with water free from objectionable volatile impurities to effect simultaneous condensation of glycerin and generation of steam from the water, and supplying steam so produced, free from objectionable volatile impurities, as the open jet steam used to promote the distillation of the glycerin.

3. The method of distilling glycerin which comprises maintaining a body of glycerin to be distilled in active circulation and agitation by introducing a number of steam Jets therein, causing the circulating glycerin to come into intimate indirect contact yvith lhigh pressure saturated steam to heat the glycerin, with condensation of water from such high pressure steam, drawing of! the condensed Water and reducing the pressure thereon, bringing such condensed water while hot into indirect heat interchanging relation with glycerin vapors distilled from said body, to effect simultaneous condensation of glycerin and generation of steam from said condensed water under a lower pressure, passing the steam so generated into the `body of glycerin in the vform of a number of jets,

and regulating the distillation and condensation to effect condensation of a large part of the glycerin distilled as concentrated glycerin requiring no further redistillation.

4. The improvement in the distillation ofv glyc-` erin with the aid of indirect heating by high pressure steam and direct introduction of superheated steam which comprises eifecting thorough and uniform heating ot the glycerin by discharging a plurality of Jets of th'e superheated steam into a body of glycerin undergoing distillation and causing the glycerin to circulate rapidly over the heating surface to avoid local overheating, condensing water from the high pressure steam, re-

ducing the pressure on the water while still hot.

bringing the water while still hot into indirect contact with vapors generatedl from .said botbfofm glycerin to enect simultaneous condensationciv glycerin in a concentrated state and 'generation' of steam from said 'water at a lower pressure, vpassing steam so generated into the body of glycerin to eifect the. rapid circulation thereof over the heating surfaces, and preheating the steam so generated by passing it into indirect contact with the body of glycerin undergoing distillation before discharging it into said body.

5. The improvement in the distillation of glycerin with the aid of open Jet steam and diminished pressure and with heating of the glycerin being distilled by indirect contact with high pressure steam and with economy in steam Vconsumption which comprises eecting partial condensation of the glycerin vapors thus formed as high grade concentrated glycerin by bringing it into indirect heat interchanging relation with distilled water at a low pressure to eiIect simultaneous generation of steam from ,said water and partial condensation of the glycerin, supplying steam so generated as the open jet steam to aid in the distillation of the glycerin and to effect rapid circulation of the glycerin over the surfaces heated by the highv pressure steam, causing condensation of water tromthe high pressure steam and supplying water so condensed, at a lower pressure as the distilled water to be vaporized to generate the steam for the open jet steam, passing the remaining uncondensed glycerin vapors and admixed steam, etc., in indirect contact and in general countercurrent flow with cold water to effect substantially'complete condensation of glycerin and simultaneous heating of the water during such general countercurrent indirect contact and supplying additional heat by indirect contact with the condensed glycerin, at the end of such countercurrent contact to effect concentration of the glycerin, Whereby the remainder of the glycerin, remaining after the partial condensation of high grade concentrated glycerin, is also condensed and recovered as concentrated glycerin requiring no further redistiilation or concentration.

6. The improvement in the distillation of glycerin with the aid of open jet steam and diminished pressure and with heating of the glycerin being distilled by indirect contact with high pressure steam, which comprises partially condensing the distilled glycerin by bringing the vapors in indirect contact with pure water to be distilled, and with simultaneous partial condensation of high grade concentrated glycerin and generation of steam from such water, supplying the resulting steam as the open Jet steam to promote the distillation of the glycerin, completing the condensation of the glycerin by passing the glycerin vapors and admixed steam, etc., into indirect contact withcold water with general countercurrent flow of the water and glycerin and with simultaneous condensation of aqueous glycerin and heating of the water, regulating the supply oi water to effect substantially complete condensation of the glycerin as dilute glycerin, regulating the countercurrent flow of water and vapors rto effect concentration of dilute aqueous glycerin to produce a more concentrated glycerin, and further concentrating such glycerin by indirect contact with steam generated from the pure water rst mentioned, whereby the glycerin condensed both during vthe first partial cony densation and during the further complete condensation is recovered as concentrated rened glycerin.

7. The improvement in the distillation of with the aid of Yopen .let steam and lr `dininished pressure and with heatingv of the glycerin being vdistilled'by indirect contact with high pressure steam which comprises heating a body of glycerin by indirect contact thereof with p @elect und uniIorm circulation of the over the submerged heating surfaces, the

fstmmnrzsaldjets beingobtained bysupplyingfroln said hixhpressure steam,

:Ime: reduction in pressure. and passing it into montant with glycerin vapors distilled of glycerin and with simultaneous lmndenxsonof glycerin and generation o! steam 113. .'lhe inw-ther improvement in the method of @lilium-i1 the condensed water from the o www steam, while at ahightemperature, hasitsmmsure reduced to eiIect partial evaporaition ithemnt, and in which steam resulting trom an is into indirect contact n lthithemdeglyoerintobe distilled.toei!eet 9. 'rhefurtherimxmnneshlne www. of claim 5 in which the ilunl Mw @i the glyeerinbwgenenl i wateriseleetedbypldngthe upwardly in indirect mnildt I inswxiteriseimsedtoilwwraiityofstasineldmdwlda mi u .W. winmx 0f 'metw vm: Hmmm" it@ mmv @dawnm streams onship 1:: iing'the wardlyin aplunliiad in intimate hat, withsaidwaten'we liquidslyeerh 'otsaidgbeerinnm' 

